How to rewrite sbull_request in ldd3 for current kernel?

[张云]

> On Mar 20, 2016, at 2:25 PM, Ruben Safir <ruben at mrbrklyn.com> wrote:
> 
> On Sun, Mar 20, 2016 at 01:58:47PM +0800, 张云 wrote:
>> Thanks!
>> I have another question if it is possible to rewrite the data transfer function avoiding the bio complexity? 
> 
> what is the bio complexity that you are refering to?
> 

I don’t think request’s bio is much complex.
I want to rewrite the data transfer function as simple as possible 
for getting my driver working even without the knowledges of bio, like the sbull_request.

>> 
>> Yun Zhang(张云)
>> 
>>> On Mar 20, 2016, at 8:13 AM, Dongli Zhang <dongli.zhang0129 at hotmail.com> wrote:
>>> 
>>> Please refer to https://github.com/21cnbao/training/tree/50506cf04bc5616e0c3f3285dbb006c54deb1c53/kernel/drivers/vmem_disk
>>> 
>>> Dongli Zhang (张东立)
>>> http://finallyjustice.github.io
>>> 
>>> 
>>> ________________________________
>>>> From: zyunone at 163.com 
>>>> Subject: How to rewrite sbull_request in ldd3 for current kernel? 
>>>> Date: Sat, 19 Mar 2016 21:22:19 +0800 
>>>> To: kernelnewbies at kernelnewbies.org 
>>>> 
>>>> Hi, 
>>>> I am reading the book, Linux Driver Development 3. 
>>>> In the chapter on block driver of this book, I need some help to 
>>>> rewriting the sbull_request since the kernel’s block API was changed. 
>>>> 
>>>> The sbull_request code: 
>>>> /* 
>>>> * The simple form of the request function. 
>>>> */ 
>>>> static void sbull_request(request_queue_t *q) 
>>>> { 
>>>> struct request *req; 
>>>> 
>>>> while ((req = elv_next_request(q)) != NULL) { 
>>>> struct sbull_dev *dev = req->rq_disk->private_data; 
>>>> if (! blk_fs_request(req)) { 
>>>> printk (KERN_NOTICE "Skip non-fs request\n"); 
>>>> end_request(req, 0); 
>>>> continue; 
>>>> } 
>>>> sbull_transfer(dev, req->sector, req->current_nr_sectors, 
>>>> req->buffer, rq_data_dir(req)); 
>>>> end_request(req, 1); 
>>>> } 
>>>> } 
>>>> 
>>>> I have rewritten the code above into: 
>>>> 
>>>> /* 
>>>> * The simple form of the request function. 
>>>> */ 
>>>> void blkplay_request(struct request_queue *q) 
>>>> { 
>>>> struct request *req; 
>>>> 
>>>> while (!blk_queue_stopped(q) && 
>>>> (req = blk_peek_request(q)) != NULL) { 
>>>> struct blkplay_dev *dev = req->rq_disk->private_data; 
>>>> blk_start_request(req); 
>>>> if (req->cmd_type != REQ_TYPE_FS) { 
>>>> printk (KERN_NOTICE "Skip non-fs request\n"); 
>>>> blk_end_request(req, -EIO, 0); 
>>>> continue; 
>>>> } 
>>>> 
>>>> /* I don’t know how to write the statement below */ 
>>>> blkplay_transfer(dev, req->sector, req->current_nr_sectors, 
>>>> req->buffer, rq_data_dir(req)); 
>>>> 
>>>> blk_end_request_cur(req, 0); 
>>>> } 
>>>> } 
>>>> 
>>>> 
>>>> Is the rewrite proper? 
>>>> 
>>>> 
>>>> 
>>>> The compiler can’t compile it because the request struct no longer has 
>>>> 
>>>> the field of ‘sector’ and ‘current_nr_sectors’. I have read the kernel code 
>>>> 
>>>> about the request struct, the kernel code said the __data_len and 
>>>> __sector field of 
>>>> request struct is internal so that we shouldn’t access them directly. 
>>>> 
>>>> How could I rewrite it ? Thanks. 
>>>> 
>>>> _______________________________________________ Kernelnewbies mailing 
>>>> list Kernelnewbies at kernelnewbies.org 
>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies 
>>> 		 	   		  
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>> 
>> 
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